Using classic Outlook for Windows in business environments
Which Outlook do I have?
If you click "File" on your Outlook main menu and there is no "Options" choice, then you have New Outlook for Windows or Outlook Web.
New Outlook for Windows and Outlook Web
No solution. All you can do is Vote for and Comment on these Feature Request.
(You must "Sign In" at the top right of the Feedback page before you can vote).
https://feedbackportal.microsoft.com/feedback/idea/7e6cf897-bd52-f011-95f3-7c1e5299279a
https://feedbackportal.microsoft.com/feedback/idea/3c6ddb68-6e52-f011-95f2-7c1e52a55eeb
Classic Outlook
See the answer by @Koech Kip in this thread.
File -> Options -> Advanced -> Outlook panes Uncheck Show Apps in Outlook